Semiconductor Electronics: Materials, Devices and Simple Circuits — Physics STD 12 Science — Question

A radio transmitter radiates 1 kW power at a wavelength 198.6 metres. How many photons does it emit per second

(a)

(b)

(c)

(d)

Hydrogen atoms are excited from ground state of the principal quantum number 4. Then the number of spectral lines observed will be

(a) 3

(b) 6

(c) 5

(d) 2

Assertion   :   Bending a wire does not effect electrical resistance.

Reason       : Resistance of wire is proportional to resistivity of material.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

The internal resistance of a primary cell is 4 ohm. It generates a current of 0.2 amp in an external resistance of 21 ohm. The rate at which chemical energy is consumed in providing the current is

(a) 0.42 J/s

(b) 0.84 J/s

(c) 5 J/s

(d) 1 J/s

Capacitiors are used in electrical circuits where appliances need more:

1V equals:

Retina of eye acts like ........ of camera

(a) Shutter

(b) Film

(c) Lens

(d) None of these

What happens to fringe width in the Young's double slit experiment, if it is performed in glycerine instead of air?

"The work per unit of charge required to move a charge from a reference point to a specified point, measured in joules per coulomb or volts. The static electric field is the negative of the gradient of the electric potential." comments are given below, select the correct one:

Which of these is a correct definition of conventional current?